Hypodermic injection device having cannula covered with resilient sheath

ABSTRACT

A hypodermic injection device comprising a cartridge holder having a cylindrical body open at one end and closed at the other end, the closed end being provided with an aperture, a cartridge including an ampoule with attached cannula within the holder, the cannula being directed toward the holder&#39;&#39;s closed end, the ampoule including a cylindrical sleeve slidably carrying a piston, the sleeve being open at one end and having a necked portion at the other end to receive a hub mounting the cannula, fluid medicament in the sleeve between the piston and cannula, a spring power assembly for moving the cartridge forward and for injecting the fluid medicament carried in the ampoule, a safety assembly for controlling actuation of the spring power assembly, and a resilient sheath covering the cannula to maintain the cannula in sterile condition.

United States Patent 1191 Sarnoff et al.

[ ]*May 13, 1975 [54] HYPODERMIC INJECTION DEVICE 3,403,679 10/1968Sinclair et a1. 128/218 F A COVERED WITH 3,702,609 11 1972 Steiner128/218 F 3,712,301 1/1973 Sarnoff 128/218 F [75] Inventors: Stanley J.Sarnoff; George B. FOREIGN PATENTS OR APPLICATIONS Calkins, both fBethesda Md 1,514,210 H1968 France 128/218 F [73] Assignee: SurvivalTechnology, Inc., Bethesda, Primary Examiner Richard Gaudet AssistantExaminer-J. C. McGowan =1 1 Notice; The portion of the term of thisAttorney, Agent, or Firm-Witherspoon and Lane patent subsequent to Mar.19, 1991, has been disclaimed. 1 1 B RACT A hypodermic injection devicecomprising a cartridge 2 F A 1 73 2] fled 9 holder havmg a cylmdncalbody open at one end and [21] Appl. No.: 384,682 closed at the otherend, the closed end being provided with an aperture, a cartridgeincluding an ampoule l. 12 with attached cannula Within the holder thecannula 4 5 5 being directed toward the holders closed end, the am- [58]Fie'ld 218 DA poule including a cylindrical sleeve slidably carrying a128/218 NV M R piston, the sleeve being open at one end and having a 218g necked portion at the other end to receive a hub mounting the cannula,fluid medicament in the sleeve between the piston and cannula, a springpower as- [56] References cued sembly for moving the cartridge forwardand for in- UNITED STATES PATENTS jecting the fluid medicament carriedin the ampoule, a 2,752,918 7/1956 Uytenbogaart 128/218 F afety assemblyfor controlling actuation of the spring 2,847,995 8/1958 Adams 128/218 Npower assembly, and a resilient sheath Covering the ;6 cannula tomaintain the cannula in sterile condition. 3:136:313 6/1964 EnstrBm eta1. 128/218 F 7 Claims, 3 Drawing Figures 2|4 lo I06 164 I38 I29 101 1132 so 136 14s PATENTEU HAY 1 ems 882,863

HYPODERMIC INJECTION DEVICE HAVING CANNULA COVERED WITH RESILIENT SHEATHSUMMARY OF THE INVENTION This invention relates to injection devices ofthe gun type wherein spring power means drives an ampoule and cannula toinsert the cannula and then inject the medicament. The cannula isprovided with a resilient sheath to maintain the cannula in sterilecondition at 'all times prior to injection.

In the device of this invention, the ampoule and attached cannula areslidably carried in a cylindrical holder which is closed at the endhousing the cannula except for an aperture through which the cannulapasses when the unit is actuated. A spring power assembly drives aplunger which engages the ampoule to drive the ampoule and cannulaforward causing the cannula to travel out through the aperture in theclosed end of the cylindrical holder and to enter the locus which is toreceive the fluid medicament. Continued movement of the plunger, afterplacing of the cannula in the locus, forces a piston in the ampouleforwardly to inject the medicament. During this action, the resilientsheath positioned on and over the cannula is held within the closed endof the cylindrical holder and is pierced by the end of the cannula as itproceeds forwardly. As the cannula continues forward, the sheath iscompressed between the closed end of the cylindrical holder and thecannula hub. This action continues until the cannula is fully extended,at which time the sheath is not quite fully compressed, thus making itpossible for the sheath to act as a shock absorber at all times duringforward travel of the cannula. Toward the end of injection, the forwardtravel of the power spring is such that its energy is less than that nowstored in the compressed sheath. Therefore, a. slight retraction of thecannula occurs during the terminal portion of the injection.

In view of the foregoing, it is an object of this invention to provide agun type injection device with a resilient cannula sheath formaintaining the cannula in sterile condition at all times prior toactuation.

It is another object of this invention to provide a gun type injectiondevice with a resilient cannula sheath to act as a shock absorber duringoperation of the device.

It is a further object of this invention to provide a gun type injectiondevice wherein the cannula is covered by a resilient sheath which uponbeing compressed when the device is actuated will react to retract thecannula a small distance during the terminal portion of injection.

IN THE DRAWINGS FIG. 1 is a longitudinal broken away view, partly insection, illustrating the sheath as applied to the cannula when theinjection device is in ready position;

FIG. 2 is a view similar to FIG. 1, showing the compressed sheath afterfiring of the injection device with the cartridge fully projected andjust prior to the forward movement of the plunger and injection of themedicament; and

FIG. 3 is a view similar to FIG. 2, illustrating a slight retraction ofthe cannula from the fully extended position of FIG. 2 which .retractionoccurs during the terminal portion of the injection.

DETAILED DESCRIPTION OF THE INVENTION 0 open end. A cartridge assembly106 is assembled in the shouldered end of the outer sleeve 100. Thecartridge assembly 106 includes a cartridge holder sleeve 104 fittedwithin the sleeve 100 and having a decreased forward end portion 153forming a shoulder 154 which fits against seat 112 provided by outersleeve shoulder 110. The extreme forward end portion 156 of the holdersleeve 104 is tapered to form a small circular aperture.

The cartridge 135 includes an ampoule cylinder 136 with liquidmedicament 146 there within and a piston 148 at one end with a cannula150 at the other end. The ampoule cylinder 136 has a necked portion witha diameter less than that of the cylinder I36 and terminates in anenlarged annular flange. The cannula 150 is secured to a cannula hub 81which in turn is affixed to the enlarged flange on the necked portion80. More specifically, cannula hub 81 comprises a reduced diameterportion 84 which is secured to cannula 150 and an intermediate body 86connected to enlarged body 88. The enlarged body 88 fits over and issecured to the annular flange of the necked portion 80 of the ampoulecylinder. Within the neck of the ampoule cylinder 136, between the innerend of the cannula 150 and the medicament, there may be interposed afluid pressure rupturable diaphragm generally like that described in US.Pat. No. 3,391,695 to Sarnoff.

The cartridge assembly 106 is assembled in the outer sleeve with thecannula 150 spaced from the apertured end of the holder 104. The overalllength of the ampoule and cannula is such that it is all containedwithin the holder sleeve 104, as illustrated in FIG. 1.

The outer sleeve 100 is of such length that it accommodates thecartridge assembly 106 in one end and receives the gun assembly 200 inthe other to complete the device. The gun assembly 200 comprises aninner gun sleeve 101 having an out turned flange 103 which fits upagainst the end of the cartridge holder sleeve 104 when the gun assemblyis inserted in the outer sleeve 100. The other end of the inner gunsleeve 101 is centrally apertured to form a hole 120. The rear outerface 122 of the inner gun sleeve 10] is planar and perpendicular to thelongitudinal axis of the sleeve for a purpose to be brought out later.

A plunger 162 fits within the out turned flange end of the inner gunsleeve 101. This plunger has a cylindrical body portion 163 and acircular head portion 164 of a diameter larger than the body portion 163and generally slightly less than that of the piston 148 in the ampoule135. The head 164 has an opening which is sized to align and correspondto the through hole 166 in the plunger body 163. The plunger head 164 isprovided with a plurality of circumferentially spaced, radiallyextending tabs 168. These tabs 168 form a diameter greater than that ofthe plunger head 164 so that the tabs will engage the end of the ampoulecylinder 136.

' Longitudinal slots 172 are formed in the plunger head 164 immediatelybehind the tabs 168. These slots are sized so that they will accommodatethe tabs 168 when they are later broken off or bent rearwardly in theoperation of the device. These slots extend throughout the length of thehead behind the tabs.

Referring to FIGS. 1 and 2, a locking detent 176 is fitted through thehole 166 in the plunger 162 and has a central body portion 178 withoutwardly extending lugs 180 on one end fitting an annular shoulder 182of the plunger head 164. The other end of the locking detent 176 isprovided with four equally spaced, longitudinally extending springydetent arms terminating in frusto-conical detent heads 186. This lockingdetent 176 maintains the plunger 162 and inner gun sleeve 101 inassembled position with a coil spring 138 compressed therebetween asfollows: A coil spring 138 is positioned over the plunger body 163 andabuts the plunger head 164 at one end and the inner face of the end wallof the inner sleeve 101 at the other. Upon compressing of the coilspring 138 sufficiently, the detent heads 186 will be cammed inwardly byengaging the periphery of the end wall opening 120 and pass therethroughwhereupon the bases of the detent heads 186 will come to rest on theplanar face 122 of the inner gun sleeve 101 to retain the plunger andinner gun sleevein assembled condition with the coil spring 138compressed therebetween. When desired, the rear planar surface 122 ofthe inner sleeve 101 may be overlaid with a metal washer 127, in whichcase it is advan tageous to provide a guide and holding flange 128 tosurround the opening 120. The flange 128 is provided with a lip portionto retain the washer in place.

As illustrated in FIGS. 1 and 2, the inner gun sleeve 101 has aplurality of longitudinally extending raised ribs 129 running from theflange 103 approximately one-half the length of the said sleeve. Anouter gun sleeve 192 fits over inner gun sleeve 101 and is sized tofrictionally engage ribs 129. The outer sleeve 192 has a closed end 194with a central aperture 196 from which extends a frusto-conical camsurface 198 sized and shaped to cooperate with frusto-conical detentheads 186 to cam said heads radially inwardly. The outer gun sleeve 192is provided with a circumferential locking rib 199 which fits in groove113 in the outer sleeve 102 to retain the gun assembly 200 in positionin said outer sleeve. It should be noted that the length of outer gunsleeve 192 is slightly less than that of the inner gun sleeve 101 so asto make certain that there will be space between the inner wall of theouter gun sleeve 192 and the flange 103 of the inner gun sleeve 101 sothat the two gun sleeves may move relative to each other to ca'mfrusto-conical detent heads 186 inwardly in operating the device.

In order to make certain that the frusto-conical detent heads 186 arenot accidentally cammed inwardly, a safety pin assembly is provided.This safety pin assembly comprises a cap 142 having a cylindrical sleeve143 sized to fit over the end portion of outer gun sleeve 192. A safetypin 144 extends inwardly from the center of the cap 142 into the openingformed by the inner portions of the detent heads 186 to thereby preventinward movement of said detent heads. The cap 142 is provided internallywith a plurality of spacer abutments 145 to assure proper positioning ofthe cap on the outer abuts the shoulder 82 formed by hub portions 84 and86. The length of the sheath is such that its closed end is slightlybeyond or spaced from the end of cannula 150. In order to make certainthat the sheathed cannula is maintained in proper alignment withaperture 158, a plurality of ribs 157 is formed on the inner face oftapered holder portion 156 surrounding said aperture. Thus, the end ofthe sheath 250 is held in necessary alignment by bearing against theconverging section of the ribs 157.

Upon the actuation of the injection device, the cartridge assembly 106moves forward whereby the sheath 250 is compressed between the cannulaend of the cartridge holder sleeve 104 and the hub shoulder 82, asillustrated in FIG. 2. The cannula sheath, in being compressed, acts asa shock absorber to gradually absorb some of the energy provided by thepower spring 138 as it drives the cartridge assembly 106 forward. Itshould be noted that at no time, even when the cannula is fullyextended, is the sheath compressed to such an extent that it would actas a solid and thereby provide no shock absorbing in such a condition.

When the cannula 150 is fully extended as shown in FIG. 2, the cannulasheath 250 will be compressed the greatest amount hence the largestreactionary force will exist in the compressed sheath in such position.As illustrated in FIG. 2, the cartridge has completed its travel underthe force of spring 138 and the forward movementaof piston 148 commencesunder the action of spring 138 to start the injection cycle. The size ofthe sheath is such that in the maximum compressed condition, as in FIG.2, the forces stored in the sheath are greater than those in spring 138when it has reached a point just short of full piston travel. At thispoint the compressed sheath 250 takes over and causes the cartridge 135and attached cannula 150 to retract slightly, as shown in FIG. 3, whilethe last stage of injection takes place. It is at this stage that theforces of the compressed sheath and the spring 138 are counterbalanced.

The importance of the sheath 250 and its multiple features is even moreimportant when consideration is taken of the fact that most of theampoule cylinders (i.e. cylinder 136 of the device illustrated) are madeof glass and hence are subject to breakage under certain amounts andtypes of shock. The shock absorbing feature enjoyed by the use of thecannula sheath of this invention contributes substantially to overallquality and reliability. Furthermore, the covering of the cannula withthe sheath provides greater ease in assembly since it is not necessaryto maintain any of the inner portions of the holder and associatedelements in sterile condition.

The type of material from which the sheath 250 can be made variessubstantially. Even so, the preferred material would be one having goodresilient characteristics such as various types of rubber andsynthetics. Shelf life is also important. By this it is meant that thematerial should retain its characteristics over a substantial period oftime and under varied conditions.

What is claimed is:

1. In a hypodermic injection device comprising a gun, a cartridge holderin operative relationship to the gun, a cartridge within the holder,said gun comprising a sleeve open at one end thereof, a plungerpositioned within the sleeve, spring power means acting on said plungertending to move it out the open end of the sleeve, restraining meanscooperating with said plunger to prevent plunger movement, safety meansacting on said restraining means to render it inoperative, saidcartridge holder comprising a hollow shell acting as a prolongation ofthe gun sleeve, said cartridge including an ampoule comprising a hollowcylindrical sleeve, a piston slidably positioned in one end thereof andmeans mounting a cannula extending from and closing off the other end, afluid within the cylindrical sleeve between the piston and the cannula,the cartridge fitting within the cartridge holder with the free end ofthe cannula within the end of the holder remote from the gun, theimprovement comprising:

a resilient sheath covering the cannula, said sheath having a closed endand an open end, the length of the sheath being sized such that whenassembled on the cannula the closed end of the sheath is not pierced bythe cannula end, and means for preventing forward movement of the closedend of the sheath whereby when the power means forces the cartridgeforward the cannula will pierce the closed end of the sheath and deliverthe fluid medicament from the ampoule sleeve.

2. The invention as set forth in claim 1 and wherein the resilientsheath comprises a resilient cylinder having a closed and an open end,the length of the sheath being sized such that the closed end thereof isspaced from the cannula end.

3. The invention as set forth in claim 1 and wherein the resilientsheath is so sized that upon forward movement of the cartridge, thesheath will be compressed between the cannula hub and the forward end ofthe cartridge holder and act as a shock absorber.

4. The invention as set forth in claim 3 and wherein the size of theresilient sheath is such that it is never fully compressed, even whenthe cartridge is fully extended.

5. The invention as set forth in claim 4 and wherein means are providedin the forward end of the cartridge holder for centrally positioning theclosed end of the resilient sheath in the cartridge holder.

6. The invention as set forth in claim 1 and wherein the resilientsheath is so sized that when it is compressed by the full extension ofthe cartridge under action of the power means the reactionary energystored in the compressed sheath will overcome the force of the powermeans and retract the cannula a small distance.

7. The invention as set forth in claim 3 and wherein

1. In a hypodermic injection device comprising a gun, a cartridge holderin operative relationship to the gun, a cartridge within the holder,said gun comprising a sleeve open at one end thereof, a plungerpositioned within the sleeve, spring power means acting on said plungertending to move it out the open end of the sleeve, restraining meanscooperating with said plunger to prevent plunger movement, safety meansacting on said restraining means to render it inoperative, saidcartridge holder comprising a hollow shell acting as a prolongation ofthe gun sleeve, said cartridge including an ampoule comprising a hollowcylindrical sleeve, a piston slidably positioned in one end thereof andmeans mounting a cannula extending from and closing off the other end, afluid within the cylindrical sleeve between the piston and the cannula,the cartridge fitting within the cartridge holder with the free end ofthe cannula within the end of the holder remote from the gun, theimprovement comprising: a resilient sheath covering the cannula, saidsheath having a closed end and an oPen end, the length of the sheathbeing sized such that when assembled on the cannula the closed end ofthe sheath is not pierced by the cannula end, and means for preventingforward movement of the closed end of the sheath whereby when the powermeans forces the cartridge forward the cannula will pierce the closedend of the sheath and deliver the fluid medicament from the ampoulesleeve.
 2. The invention as set forth in claim 1 and wherein theresilient sheath comprises a resilient cylinder having a closed and anopen end, the length of the sheath being sized such that the closed endthereof is spaced from the cannula end.
 3. The invention as set forth inclaim 1 and wherein the resilient sheath is so sized that upon forwardmovement of the cartridge, the sheath will be compressed between thecannula hub and the forward end of the cartridge holder and act as ashock absorber.
 4. The invention as set forth in claim 3 and wherein thesize of the resilient sheath is such that it is never fully compressed,even when the cartridge is fully extended.
 5. The invention as set forthin claim 4 and wherein means are provided in the forward end of thecartridge holder for centrally positioning the closed end of theresilient sheath in the cartridge holder.
 6. The invention as set forthin claim 1 and wherein the resilient sheath is so sized that when it iscompressed by the full extension of the cartridge under action of thepower means the reactionary energy stored in the compressed sheath willovercome the force of the power means and retract the cannula a smalldistance.
 7. The invention as set forth in claim 3 and wherein thecylindrical sleeve is made of glass.